My Computer is a 6 year old Dell with Windows Vista. Lately it has been freezing and crashing quite frequently. Is this a sign that it needs to be replaced ?
For starters, go into the BIOS and do a hardware diagnostic. Dell PCs have a hidden partition with diagnostic tools, usually to test the system memory and the hard drive. If it passes these tests I'd recommend you examine the memory dumps Windows usually creates when the computer crashes. Go to C:\Windows\Minidump where you should find several (or many) DMP files.
If you don't see the Minidump folder, this feature may be disabled. To enable it do the following:
1-Click Start, and then click Control Panel.
2-Double-click System, and then click Advanced system settings.
3-Click the Advanced tab, and then click Settings under Startup and Recovery.
4-In the Write debugging information list, click Small memory dump.
Once you have several DMP files download and run BlueScreenView to examine them. The information you get can be somewhat cryptic, but comparing several DMP files may allow you to detect a certain pattern. If a corrupt driver is the culprit you'll see the SYS file (or several) at the top of the list. For example, dxgkrl.sys may point to a DirectX issue, while atikmpag.sys would probably point to a video driver problem. If you see the same file mentioned in several DMP files you could probably reinstall/update the video driver, antivirus program, or whatever application is referenced.
Good luck.